1. Field of the Invention
The present invention relates generally to the heat treating process known as annealing. More particularly, the present invention relates to the provision of and the use within annealing processes of a particularly long-lived and durable type of convection diffuser plate hat incorporates a significant safety feature in the form of at least one endless loop of steel chain that is embedded in the cast nodular iron material of the plate structure to minimize the possibility that relatively large portions of a cracked or broken convection diffuser plate will shatter or separate unexpectedly.
2. Prior Art
Working in the environment of a steel production plant has always involved elements of risk Massive machinery is used to process massive quantities of product as by using extreme heat and high pressure, with cranes and other mechanisms being used to move quantities of product between workstations and/or between workstations and areas of storage.
In such an environment, it is desirable to take precautions to avoid breakage of machine components. However, because machine component breakage cannot be entirely prevented, it also is desirable to take precautions to assure that if and when component breakage occurs, the resulting injury to persons and the resulting damage to property is minimized.
The reasons why component breakage occurs are many and varied. Useful life often is significantly diminished due to the deleterious effects of repeated cycles of heating and cooling to which many components in a steel production facility are subjected. Likewise, as heavy components and heavy quantities of product are moved about as by cranes, unintended impacts sometimes take place. These and many other factors contribute to component failure, and can cause components to crack, break and/or shatter unexpectedly.
In an annealing furnace, a fixed base typically is used to support a vertical stack of coils of steel product; a open-bottom tank-like enclosure is lowered in place to enclose the stack and to mate with the base to establish a controllable environment within which the coils are enclosed; and, the coils are heated and then cooled in this environment, in a controlled manner that causes properties of the steel to be desirably enhanced.
Maintaining a controlled convection flow of gases within the environment of an annealing furnace is an important aspect of the annealing process. Convection flow is permitted to take place between adjacent end regions of the stacked coils by inserting heavy, complexly configured convector plates between the adjacent end regions of adjacent pairs of coils. The convector plates typically are of substantially annular shape so as to define substantially concentric inner and outer diameters, and have formations that define a plurality of radially extending gas flow passages extending between outer and inner diameter regions of the convector plates.
Of all of the components that comprise an annealing furnace, its convector plates tend to be particularly prone to failure. Due to the need for the convector plates to be able to support multi-ton coils of steel in stable, spaced, stacked relationship, the convector plates are, of necessity, quite heavy, and typically are moved into and out of position using a crane. Due to the need for the convector plates to define a plurality of substantially radially extending gas flow passages, the convector plates tend to be relatively complexly configured structures that employ an array of formations which, when viewed in cross section, vary from relatively thick to relatively thin. Thus, despite their massive size and weight, convector plates often are of relatively breakable character and benefit from being handled relatively gently.
Because convector plates are subjected to repeated cycles of heating and cooling, and because they often are moved about relatively roughly as coils are being "stacked" and "unstacked" before and after their being treated within the enclosures of annealing furnaces, it is not unusual for cracks to form that lead to breakage. Nor is it unusual for convector plates to "shatter" or to fail as by literally "falling apart" while they are being moved by cranes. If a convector plate shatters or breaks such that sizable pieces are caused to drop from a crane, serious injuries and/or significant property damage can result. Thus, to the extent that the longevity of the service life of convector plates can be enhanced, and to the extent that shattering or catastrophic breakage of failed convector plates can be minimized, these are worthy objectives.
The referenced Parent Case seeks to address such needs by providing convector plates that are cast from nodular iron, and that are reinforced with rigid steel bars. While the use of nodular iron has proved to enhance the longevity of service of convector plates, the use of rigid steel reinforcement bars has not proven to be particularly helpful in holding together the parts of broken convector plates, whereby the problems of shattering and of sizable pieces of failed convector plates dropping from cranes during transport has remained unsolved.